The Volvo P1800 Station Wagon Rear Glass

This car :
Always fascinated me. it had the rear window that was hinged directly to the glass-there was no metal frame. Did these windows break frequently? Nobody seems to do this these days…why?

Back in the late 1980s I had a Citroen AX which was a hatchback. The rear hatch was a sheet of glass (hinged at the top) and then the plastic lower half was also attached to the glass.

The rear hatch certainly had a reputation for breaking but I had no problems with mine and I always felt the danger was overstated.

Meanwhile Volvo produced a P1800 inspired coupe until 2013, the C30, which also has the seamless glass hatch:


The Peugeot 107, and the near-identical Toyota Aygo and Citroën C1.
Have an all glass rear windo without any serious issue, ant between them have very large sales.

A lot of 90’s SUVs had a similar thing with the pop-up frameless glass over the tailgate. I had an Isuzu Rodeo with one that one day inexplicably shattered into smithereens when I opened it.

the later models of pinto/bobcat also came equipped with full-glass hatches.

Why isn’t it used ? safety standards were changed, to say that all side and rear glass was to be made of safety glass. NOT toughened or laminated.

You can’t make a door out of safety glass, you slam it closed and it shatters ?
Can’t do that.
Also, I fear there was a longevity problem… the aerodynamics keeps pulling the rear window OPEN… so the seal is undone and dust and rain gets in… perhaps when new the seals were working, but after just a few years, its not working properly and the warranty claim is for repairing electrics, carpets, paint, even fuel tank and other components in the rear of the vehicle, as well as the rubber seal… So longer warranties rules it out ?

Also you have noted that the glass would be subject to breakage due to impact… what happens with toughened glass is that when its new , its quiet strong, but when the scratches and chips accumulate, it becomes weak… a real safety hazard given that a person is going to be right there with this sheet of glass at their body… then it brakes into large pieces, if its toughened…

If it was laminated, well that’s fine for the permanently mounted windscreen, but I think the damage from usage (scratches and chips to the outside edge) , and the extra vibration acting on the glass, would see the laminate fall apart… back to the warranty issue, longer warranties means the design has to have the glass lasting longer…

Buick roadmasters in the 90’s had the hinges on the glass as well and they were plenty durable.

Reading about the strength of glass technology is really fascinating.

Lots of bog standard cargo vans have the same arrangement; the windows in the back doors can be popped open a couple inches for venting, hinges attached directly to glass.

If you look around a bit you will see lots of examples, particularly in vehicles from mid to late eighties. Sun roofs, side windows, canopy windows; frameless with mechanisms attached directly to glass.

If you want to look in homes, higher end shower glass doors are also frameless. Not only are the hinges bolted directly to glass on both ends, the panel edges are fastened to the walls with a thick bead of silicone and sometimes a metal bracket at the top. Plenty of examples in commercial buildings as well. Take a look around at the mall or bank, plenty of frameless glass doors and panels.

Glass like anything just has to be properly designed for its application.